An angiographic examination or intravascular treatment using an X-ray diagnostic apparatus uses a contrast medium to grasp the shape and position of a blood vessel. In general, the concentration of a contrast medium to be injected into an object is fixed within one procedure. The blood vessel contrast on an angiographic image captured while a contrast medium is injected in an object varies depending on imaging conditions (e.g., an object, X-ray conditions, and an imaging angle). The contrast medium in use does not always have a proper concentration. For this reason, depending on the object, a contrast medium having an excessively high concentration is used sometimes. In another case, a desired blood vessel contrast cannot be obtained on an angiographic image due to the low concentration of contrast medium, and X-ray imaging is performed again upon changing contrast medium conditions such as a contrast medium concentration and an injection rate.
Unnecessarily injecting a contrast medium into an object in this manner may increase the possibility of occurrence of nephropathy in the object. Therefore, in order to reduce the amount of contrast medium used, an X-ray diagnostic apparatus is required to be capable of predicting and displaying a blood vessel contrast in an angiographic image before capturing of the angiographic image.